Natural heavy metal and metalloid concentrations in sediments of the Minho River estuary (Portugal): baseline values for environmental studies

Abstract

Forty-nine surface sediment samples from the Minho estuary sector between Tui and Caminha were analyzed for grain-size contents, Al, As, Cr, Cu, Hg, Li, Pb, Sn, and Zn concentrations. Selected heavy metal (Cu, Cr, Hg, and Zn) and metalloid (As and Sn) distributions were normalized against Al and Li with the main goal of compensating for natural grain-size variability and to separate natural from anthropogenic contributions, by using a combination of normalization techniques (definition of regional geochemical baselines (RGB) and determination of enrichment factors (EF)). Lead did not reveal a significant relationship with Al and Li. Aluminum explained more variance than Li for As, Cu, Hg, and Zn. Assuming the general non-impacted metal character of the Minho River estuary sediments, RGBs are defined for differentiating between natural and anthropogenic contributions. Based on RGB defined for each heavy metal/ metalloid, the degree of enrichment is estimated through the determination of EF. Despite the relatively low total heavy metal and metalloid concentrations, the defined RGB identifies a set of samples characterized by presenting As, Cu, Cr, Hg, and Zn enrichments relatively to expected natural levels. Mercury is the element showing the highest level of enrichment relative to the baseline values being spread through all the study area. Tin present enrichments relatively to Al and or Li always lower than 1.5 suggesting natural contributions.

Metal levels and accumulation patterns of sea lamprey ammocoetes (Petromyzon marinusLinnaeus, 1758) from a tidal freshwater habitat

“…Our results point out that ammocoetes of sea lamprey P. marinus from Minho watershed can accumulate considerable quantities of some elements, but mainly Fe and Zn and might work as input of metals into trophic webs. Low concentrations of Cr and Pb are in accordance with consideration of the Minho watershed as a metal uncontaminated and a metal-pristine area (Reis et al, 2009;Mil-Homens et al, 2012;Santos et al, 2012).…”

“…This pattern slightly differs from metal levels in sediment samples of river Minho (Cd < Cu < Cr < Pb< Zn < Mn< < Fe) (Paiva et al, 1993;Moreno et al, 2005;Lyra, 2007;Mil-Homens et al, 2012).…”

Can biotic indicators distinguish between natural and anthropogenic environmental stress in estuaries?

“…The relationship between the densities of taxa belonging to different AMBI ecological groups and the level of heavy metal contamination was explored using a shade plot and coherent species analysis. fraction of sediments and is commonly used as a -normalizer‖ when assessing the degree of anthropogenic enrichment (Schropp et al, 1990;Ho et al, 2012;Mil-Homens et al, 2013). This is because its concentration is related to the geology of the sediment and is thus not affected by anthropogenic sources (Schropp and Windom, 1988).…”

Geochemistry of terrigenous sediments in surface water from ore and okitipupa southwest, Nigeria

“…Sediments have been described by many authors as the reservoir of numerous chemicals andalso a pivotal influence in water contamination (Mil-Homens, et al, 2013;Yu et al, 2001;Sakan et al, 2009;Wepener, and Vermeulen, 2005;Mil-Homens et al, 2007;Shakeri and Moore, 2010;Yang et al, 2009). The upsurge of industrialization and population have engendered harmful chemicals and elemental pollutants that are always injected into the soils and sediments through numerous anthropogenic activities which preclude: atmospheric deposition, industrialization, agricultural activities and riparian anthropogenic activities, where chemicals and metals are produced.…”